This invention relates to shims for adjusting the combined width of multiple blade dado saw blade sets.
Grooves known as "dados" and similar formations such as rabbets or rebates have long been important in woodworking, particularly in furniture and cabinet construction. A variety of methods have been used for cutting dados and rabbets, including plow planes, chisels, routers and saws. Circular saw dado-cutting devices include multiple blade cutter sets and "wobble" type cutters in which a saw blade having eccentric washers is made to wobble as it rotates so that the resulting saw groove is wider than the blade itself. While the width of the kerf cut by such a "wobble" type dado cutter is infinitely adjustable between the actual width of the blade and the maximum possible wobble, such dado cutters machine a groove with an arcuate bottom and present other drawbacks. Accordingly, multiple-blade dado cutter sets remain popular for use with circular saws. Such sets normally include two relatively conventional circular saw blades and several two or four tooth cutters or blades having substantially the same cutting diameter as the circular saw blades in the set. The two or four tooth blades are stacked between the round blades in a combination that results in the desired combined blade width. Typically, the kerf cut by each blade exceeds the thickness of the same blade in the area of the blade adjacent to the blade arbor hole, by virtue of tooth set, tooth thickness or both. In use, the blades are staggered so that gaps in one blade accommodate the teeth that overhang from an adjacent blade.
As will be appreciated, the nominal widths of cut possible utilizing such a set are multiples of the widths of the blades stacked together at a particular time. Accordingly, in order to adjust the total cutting width by an amount less than the thickness of the thinnest blade associated with such a dado blade set, one or more shims must be used between blades. Paper, pasteboard, adhesive tape, and brass sheet materials of various thicknesses have previously been used for such shims, and they have typically been in the form of a washer, that is a disk with a centrally-located hole slightly larger in diameter than the saw arbor.
While such disks can be successfully used to adjust dado multiple-blade set width, they are inconvenient to use and typically require removal of the saw arbor nut, arbor washer and one or more blades of the dado head set in order to add or remove shims. This frequently must be done several times before a desired cutting width is achieved.